The following screenshot produced by latex-dvips-ps2pdf and the clipping is well done.

\documentclass{article}
\usepackage{xcolor}
\usepackage{pstricks,pst-func}
\newpsstyle{gridstyle}
{
gridwidth=0.4pt,%default: 0.8pt
gridcolor=red!20,%default: black
griddots=0,%default: 0
%
gridlabels=3pt,%default: 10pt
gridlabelcolor=blue,%default: black
%
subgriddiv=5,%default: 5
subgridwidth=0.2pt,%default: 0.4pt
subgridcolor=green!20,%default: gray
subgriddots=0%default: 0
}
\psset{style=gridstyle}
\newpsobject{psGrid}{psgrid}{}
\begin{document}
\noindent%
\renewcommand{\pshlabel}[1]{\bfseries\tiny #1}% for x-axis
\renewcommand{\psvlabel}[1]{\bfseries\tiny #1}% for y-axis
\psset{yunit=0.4cm,xunit=0.5cm}
\centering\begin{pspicture*}(-4,-5)(4,15)
\psGrid
\psaxes[Dy=2,Dx=2]{<->}(0,0)(-4,-5)(4,15)
\psset{linewidth=1pt,linecolor=blue}
\psPolynomial[coeff=-1 0 1,linecolor=red]{-4}{4}
\psPolynomial[coeff=-1 0 1,xShift=1,linestyle=dashed]{-4}{4}
\rput[rt](3,12){\textcolor{red}{$f(x)$}}
\rput[lt](2.5,1){\textcolor{blue}{$g(x)$}}
\end{pspicture*}
\end{document}
But the following screenshot produced by xelatex and the clipping is bad done

Why cannot XeLaTeX clip my PSTricks graph plot correctly?
Last edit: After updating Miktex packages, xelatex clips the graph correctly.
xdvipdfmx. Your code may run correctly with texlive (on a linux system I would say). – pluton Jun 05 '11 at 18:05xdvipdfmxwhich should be already solved for next update. – egreg Jun 05 '11 at 20:56